Wait! California's Obsidian Dome is NOT a Lava Dome? Geologist Explains 

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My dad was a geologist. More specifically a volcanologist. I've been around this stuff as far back as I can remember.I love your videos! They bring back many very fond memories for me. I would love to hang with you sometime. It would be an honor for me.

I appreciate your (again) clear explanation of how glass formed versus other minerals types-

Love this Mono Lake series!

Wow! I've been fascinated by rocks since I was a little girl. Thanks for this. I see I wasn't just "losing time" looking at "uninteresting things".

I’m thoroughly enjoying your studies of my area of California. I love camping along the stream that is just east of this dome. I’ve collected so many cool pieces of obsidian there. 😃 And whenever someone asks me the directions to obsidian dome, I’ll say “you mean Obsidian Coulee”. 🤣

I tend to think of obsidian as a super cooled liquid.

Like always… I love learning from your videos professor 😊

Excellent as always! When I hear the word 'coulee' I always think of box shaped valleys like Grand Coulee and Moses Coulee in Washington State which have water flows as their origin. Apparently 'coulee' can also be used for these elongated domes/flows. A quick search on the Internet explains that 'coulee' originates from the French 'couler' which means 'to flow' . Language can be as fascinating as geology!

a true teacher. Seriously. Well done chap. We are lucky to have you and your passion. Thank you for being an amazing human. Someday the lack of $ will not prevent higher learning.

Another great explanation of our incredible planet. I used to drive from San Diego to California City to support aerial filming of commercials in the rugged hills of that area, as I approached California City, I was always amazed at the volcanic topography of that area. The map you are referring to in this video, finally explains how that area of California was formed and is still being formed, truly enjoy your exploration and explanations, great stuff, stay safe and keep up the great work. Thanks

Glass Mountain in Shasta area has the sharp tool making obsidian. I’ve been sliced many times handling that stuff.

I had no idea these volcanoes existed. Thank you for sharing this. Amazing.

The red "crust" could be airfall tephra that got incorporated into the flow, and "baked" since its pretty common to see ash and clay layers between lava flows that have been baked into a peach/ruddy colour :) Also the white banding in the obsidian at the end of ya video is GAWJUS. Would be great to go from the Salton Buttes, to the Mono-Inyo Craters, and then up to Little Glass Mountain, and sample all the different colours and varieties of obsidian.

Thank you again,you are a great teacher!

The small crystal formation inhibits the propagation of concoidal fracturing which is critical to flint knapping and creating amazing obsidian artifacts. I find there are great sources of clear or ribboned black and red obsidian from the Mt. Konocti area of Clear Lake, and even better material up near Medicine Lake (Northern Ca) near Glass Mountain.

Im in my 70’s, my parents were military and we traveled in the west a lot. I must have been about 4-5 at most. We visited a place that was large glassy black rolls that looked like frozen lava waves! I climbed and jumped all over them! My parents were not cautious people. Ive never found where this was. But remember it was glassy and black. Any ideas where this could have been?

Thank you for a Great Day Out on 395! Love the road, love the rocks...so cool you are doing this work.

Thank you again for more about my favorite part of the Sierra, Thanks also for putting the written name in the vid!!

Thanks for all this information. I have heard of volcanos in this area of California for many years but gained no explanations of them. It is easy to see that the crystals in the obsidian would affect the quality. In anthropology I have learned small amounts about knapping. I have gathered some obsidian in the past but my dream of learning to knap just never gained enough momentum. I'm looking forward to learning more. It's interesting about the coulee definition. In Washington state a coulee is a completely different type of feature.

I have never seen so much obsidian before! 😲Interesting stuff, thanks for the explanation of how it formed.

Love Obsidian dome and the mono craters! Took my nieces there a few years ago and was showing them the different types of volcanic rock there as you covered - pumice, rhyolite, and of course obsidian. I have some nice bishop tuff samples and a football sized piece of pumice I love to toss to people and have them brace for a big heavy rock.....

Very cool! Glad to hear about the terminology of this "dome" and rock types. I've been visiting this dome/coulee almost every year and brought friends along to see the other-worldly terrain at the top. I studied geology in college so i always give them a basic explanation. I might add some details from your explanation to my own next time 👍

Thank you! I am learning so much and appreciate your hard work.

These structures have always facinated me. Excellent video and so easy to understand. Thank you!

Fantastic explanations for the various formations of rock and minerals! Thank you so much for visiting this area, and looking forward to future exploring videos by you

Thank-you Shawn, for another interesting & informative episode!

I’ve seen these obsidian rocks in a couple landscapes and always wondered where they came from, they look exactly the same. Great garden rocks.

My wife and I were there 6 or 7 years ago. Visited the obsidian near Mono Lake also. It's a very interesting area.

Fantastic! I really like the context comparing this with Wilson Butte and the closeups of the different rock types layered together. Talking about lava domes reminds me incidentally of Novarupta and if you ever have a chance to do a deep dive into that eruption and what the latest ideas are about the crazy (?) plumbing system there it could be really helpful (most of the materials I've found online are a bit confused). Thanks again for all your work and sharing with us!

Neat stuff, Shawn. 👍

I appreciate you. You are very clear and easy to understand. Beautiful stuff

When that section of CA395 (near the rest area) was freshly upgraded about 40 years ago I collect a few really deep black glassy obsidian samples. They are totally different than those in this video and they still reside in our back yard today.

Great explanation of the formation of Obsidian Dome. There are also some large rhyolite domes or flows in the Central Andes. I had not heard the term coulee used for these formations, but I am not a volcanologist. The interesting thing is that they may be an analog for volcanic features on Venus. They look similar to the Venusian features. We used to jokingly call them “cow patty” flows from the satellite images.

Hey Shawn, I drive this region on average once a week and never cease to enjoy drive by theorizing formations of the region. Thanks!

Slow sticky silica rich lava forming obsidian - that’s a new to me! I’d always thought it was due to rapid cooling. Also impressive that a basic magma could become so silica rich through partial melting a granite.

thank you, what an interesting video! I love Panum Crater very much, Mono Lake is just one of my favorite places on earth and it's one of the best places to enjoy it, but the obsidian also makes the most interesting sounds when you walk along the path. I never made it to the other buttes along the Mono crater line... this evidently takes special preparations as they are more remote. Next time I will pass by will make some time to get there.

I love your videos. Thank you so much for making them.

Thanks for all your informative geology videos! Love each and every one of them. Question: Will you ever make a trip to New Mexico and discuss some of the geologic features there? I live in the state, I am very much interested into its geology but unfortunately have not found a Shawn Willsey or Nick Zentner yet who talks about fascinating NM geology features like the Rio Grande Rift zone, Mogollon Mountains or Jemez lineament. I just found 1 awesome 6-part series about the Valles Caldera (rocks, rivers and bones on U-tube). I know, there must be something very interesting near to where I live, because I regularly see Geology students from Texas universities with their little rock hammers climbing the outcrops at road cuts on Hwy 82, but I never dared to stop and ask, what the point of interest is… Don´t want to disturb… Pretty busy highway with limited room to pull over as well.. I have geologic maps of this area, but they don´t tell me much besides age and composition of the rock layers. Unfortunately maps don´t tell the complexity of the stories… like you do!

I nice dinner field trip for me, thanks Shawn. I have stopped at Wilson Butte many times with friends and my kids to show them obsidian in place. I need to get off the road a bit and go to Obsidian Dome for the geology and the great scenery. I grew up on the Eastern Sierra and Hwy 395 is still my favorite drive. Oh my Summer Field was a Poleta Folds and Papoose Flat. The skarn at Papoose is so cool because it is so narrow and towards the center the intrusive gets courser grained, a really neat teaching place.

Thx Prof. Excellent vid, as always. ✌🏻

I recently began diving deep into my state’s geography and soak up your knowledge/video’s like a stale crust of bread ;) lol. Was surprised that I hadn’t subscribed, so fixed that! I’m somewhat recently obsessed with obsidian, and studying our volcanic chain has been so fun and interesting. Places we used to take vacations have become places I dream of visiting once again to soak up more knowledge of our geological past. Tyvm for this one, for it really explains a flow and a dome, and, made me aware of why I’ve never seen a snowflake obsidian point! We live close to the State’s Indian Museum in So Cali, that houses a lifetime collection of Chumash artifacts. A Swiss chalet building, built right into the sandstone rocks on the side of a butte in the high desert. Just a thought that someday you might want to visit the anomaly of a State Park Museum, someday in your travel’s. Be well and I wish I could send you a million dollars to say thank you for what you generously share here 😊

I studied Obsidian Dome for my MSc Thesis! Brings back memories.

Very nice show.......Thanks!

🤠👍👍LOVE how you always include GPS in your videos❣

Interesting and a good place to visit - gracias!

Interesting location. Thank you.

I’ve got a nice specimen of black pumice from there, very glassy. It’s kind of heavy for a pumice and I’m not sure it would float. I’ve got a piece with flow bands as well. Totally cool. Thanks for the video.

40 years ago, when I visited that location with my father, there was a visible Obsidian Done high on the hill projected out LATERALLY from the cliff face. This dome was NOT facing up. I did not measure it but it was large enough to see from the trail at the bottom of the hill (approximately 200' below and 200' horizontally) I would guess it was about 30' wide and high, it was black and shiny and smooth. Years later I went to check it out again, but it had visibly been broken in half, and its parts had been deposited along the hill beneath the remains of the dome above. I imagine by now that structure has disintegrated entirely.

Nice, I'm trying to see some comparisons with Laugahraun in Landmannalaugar (Iceland). Obsidian there seems so pure and this whole lavaflow has such an awesome shape from the cone near Brennisteinsalda.

Wow, these stone structures look great! Finally I can have a close look of alle the landmarks Dutch mentioned in his videos. Did not know obsidian looks that great! Would be a nice material for the kitchen walls behind the sink and the stove - especially the piece at timestamp 9:33 with the fash texture. I wonder what this flash texture has caused?

Thanks!

Strange: for a flowy, sticky lava, I would expect to see more of a pahoihoi formation, but this looks more like super-scale aa. I went back to school as a midlife student in my 40s, and the geology professor included an 11-day field trip at the end of the semester. We went all through the Mono Lake area, and up 395 past Reno, exploring various features such as Lava Beds National Monument, Crater Lake, and ended up at Mt. Lassen. On a hike at Lassen, I managed to cut my finger on a piece of obsidian. Bled like crazy, but it was such a clean cut, that now, 30 years later, I can't even remember which finger it was: there is no scar. Some time after that journey, I read that obsidian is often used in hospitals as disposable scalpels! I believe it.

Another great vid. Regarding the knappability of this obsidian, it can be accomplished. The crystals of Cristobilite? are small enough not to interfere with applied pressure from percussion or pressure flaking. Many of the natural fractures of this material, show a clean sharp edge, ergo decent material for knapping. However the superb obsidian from the Mt. Lassen area of northern California may have limited the use of Obsidian Dome material by the local native people for chipped stone tool manufacture. l have knapped this material successfully. Hope you go to Mt Lassen for one of your most informative tours.

I’ve given myself a headache trying to cram so much knowledge in 😂 I keep coming up with questions all the time, maybe I need to look for some sort of course so I can understand better!

Excellent camera work,

If you ever get a chance visit and do a series of videos of Valles Calderas in northern New Mexico.

Thank you for the wonderful lesson, is that rainbow obsidian? It was beautiful.

THank you!!

Thanks for taking us up the obsidian coulie. I was noticing how similar it looks to the Lake County CA obsidian; the road cuts of Bottle Rock Road south of Mt. Konocti/Clearlake. Bottle Rock Obsidian is not in this line of Inyo flows. Is there a different line that it (ours) is part of? One over here? West of the one you are showing us today? Or is it just a random obsidian, solo, crust feature? Great to meet you.

There's northwest dextral shear along with the east-west extension, through there, yes?

I was with you on the “not a lava dome” paradigm, but lava COULEE😵. Kinda forced me fact check you…at which point another rabbit holery ensued. THAT does not look like a ravine or drainage basin?!! A geologic term with two disparate meanings!? 😵. Great stuff. Let’s keep it moving!!🤣

Tack!

Thanks

Found this very fascinating Professor Willsey particularly the various rock types including ‘gaseous obsidian’. The whole area looks amazing having taken your advice and used ‘Maps’ in 3D to do a ‘virtual drone’ flight over the area! Is there anything significant on top of the Obsidian dome? 👍

Must have been a very important source of material for points and other wtobe tools for indigenous peoples.

There is a good quality mount of obsidian called Glass Mountain in the Medicine Lake highlands west of Lava Beds National Monument in far NorthEastern CA. There's also a pumice mine nearby with really good quality pumice. Then there's all the lava tubes in the park with a lot of CA. Indian war and petroglyphs in the park!!!!

Great video as always Shawn! I see you’re using what appears to be a GoPro, but the sound quality is great. Which microphone(s) do you typically use while using a GoPro for video?

I spent a night next to South Deadman Dome. Occasionally during the night we would hear pumice boulders rolling down the sides. It was pretty cool. Is pumice actually gas-whipped obsidian? It looks like it.

¡Gracias!

"Chain of Volcanoes" would make a great Rock Band name.

The stuff with the good conchoidal fracture properties is definitely my thing. But i haul a lot of junk home that's just pretty. Crystabolite(sp?) May not be knappable but snowflake obsidian makes a great ornament. When that Lassen creek blue video drops i might drool a little

Wow!❤

I love the Obsidian Dome. Word of caution, the road in there starts along HW395. Its only about 2 miles long. It starts out fine but quickly becomes very rough. Its becomes only safely passable in a true off road 4 wheel drive, with big tires and high ground clearance. A regular SUV is not recommended. You can drive in a ways and hike the rest of the way in half hour or so.

Great video Shawn. I noticed that frothy appearance of the extruded material. That same frothy appearance can be seen at a roadcut along Hwy 93 a few miles south of Hoover dam. It is located at the top of a large basalt andesite lava flow. Is there a geological story to explain this frothy appearance? I have pictures to share. 721 like ..................

Is there any estimate on how long it was erupting for?

That is amazing its all only a couple thousand years old? The structure of it is new but the material its made up of is many millions of years old, except the obsidian parts. That would be the most recent addition to the rock record.

"Bread crust cracks" -- evocative.

Thumbs up!

So, is there a place with better quality obsidian? Years ago I was hunting north of Kennedy Medows, and I was camping near a spot and I found an area where someone spent time making points judging from all of the flakes I found. The obsidian I saw didn't have the silicon inclusions.

That obsidian might not be ideal for knapping, but the flow marks might make interesting tumbled stones or cobachons.

I always learn something from you Shawn. Well done.

The proper name for the mountain range is Sierra Nevada, often shortened to the “Sierra”, but not the “Sierras” (with an “s”). Picky for sure, but that’s how it’s said. Love your videos.

You sir are most correct, definitely not good for Knapping

Shawn I’ve bin there.

I wonder if the geology of Oregon's Glass butte is the same.

You and Nick Zenter should do something.

Have you did a piece on glass Mountain just a little Away from you just a little east

So whats the likelihood of this volcanic feild erupting in the near future, 150yrs +/- or a 1000yrs +/- ?

How does the rapid cooling necessary for obsidian formation occur? How long is "rapid" and what causes it? These things have always puzzled me and i can't find good answers !:-)

I remember going there as a kid looking for obsidian that wasn't snowflake obsidian. I found a few small pieces I had to break off with a hammer.

Did you visit Hot Creek to the south east?

The top of Obsidian Dome is all pumice. I have a big chuck of obsidian in my front yard.

Mt. Lassen is

So would this Basin be underwater when the NA plate 'snaps back' from Pacific Plate moving farther under NA?

What is flintnapping?

In the 67 and 68 we would have to drive around buttes. Are buttes really volcanos?

I thought that obsidian was formed because it quickly cooled. Is that correct? (remembering from my high school earth science class i took close to the year of this dome formation - 1350).

7:45 Is that what is sometimes known as snowflake obsidian?

Maybe you can find the cement mine😀It is reported to be in that area....